Experimental and Numerical Study on the Strain Behavior of Buried Pipelines Subjected to an Impact Load

Long-distance oil and gas pipelines are inevitably impacted by rockfalls during geologic hazards such as mud-rock flow and landslides, which have a serious effect on the safe operation of pipelines. In view of this, an experimental and numerical study on the strain behavior of buried pipelines under the impact load of rockfall was developed. The impact load exerted on the soil, and the strains of buried pipeline caused by the impact load were theoretically derived. A scale model experiment was conducted using a self-designed soil-box to simulate the complex geological conditions of the buried pipeline. The simulation model of hammer&ndash soil&ndash pipeline was established to investigate the dynamic response of the buried pipeline. Based on the theoretical, experimental, and finite element analysis (FEA) results, the overall strain behavior of the buried pipeline was obtained and the effects of parameters on the strain developments of the pipelines were analyzed. Research results show that the theoretical calculation results of the impact load and the peak strain were in good agreement with the experimental and FEA results, which indicates that the mathematical formula and the finite element models are accurate for the prediction of pipeline response under the impact load. In addition, decreasing the diameter, as well as increasing the wall thickness of the pipeline and the buried depth above the pipeline, could improve the ability of the pipeline to resist the impact load. These results could provide a reference for seismic design of pipelines in engineering. Document type: Articl

Intrinsic nonlinear Hall effect and gate-switchable Berry curvature sliding in twisted bilayer graphene

Though the observation of quantum anomalous Hall effect and nonlocal transport response reveals nontrivial band topology governed by the Berry curvature in twisted bilayer graphene, some recent works reported nonlinear Hall signals in graphene superlattices which are caused by the extrinsic disorder scattering rather than the intrinsic Berry curvature dipole moment. In this work, we report a Berry curvature dipole induced intrinsic nonlinear Hall effect in high-quality twisted bilayer graphene devices. We also find that the application of the displacement field substantially changes the direction and amplitude of the nonlinear Hall voltages, as a result of a field-induced sliding of the Berry curvature hotspots. Our work not only proves that the Berry curvature dipole could play a dominant role in generating the intrinsic nonlinear Hall signal in graphene superlattices with low disorder densities, but also demonstrates twisted bilayer graphene to be a sensitive and fine-tunable platform for second harmonic generation and rectification

Thiabendazole Inhibits Glioblastoma Cell Proliferation and Invasion Targeting Mini-chromosome Maintenance Protein 2

Thiabendazole (TBZ), approved by the US Food and Drug Administration (FDA) for human oral use, elicits a potential anticancer activity on cancer cells in vitro and in animal models. Here, we evaluated the efficacy of TBZ in the treatment of human glioblastoma multiforme (GBM). TBZ reduced the viability of GBM cells (P3, U251, LN229, A172, and U118MG) relative to controls in a dose- and time-dependent manner. However, normal human astrocytes (NHA) exhibited a greater IC50 than tumor cell lines and were thus more resistant to its cytotoxic effects. 5-Ethynyl-2′-deoxyuridine (EdU)-positive cells and the number of colonies formed were decreased in TBZ-treated cells (at 150 μM, P < 0.05 and at 150 μM, P < 0.001, respectively). This decrease in proliferation was associated with a G2/M arrest as assessed with flow cytometry, and the downregulation of G2/M check point proteins. In addition, TBZ suppressed GBM cell invasion. Analysis of RNA sequencing data comparing TBZ-treated cells with controls yielded a group of differentially expressed genes, the functions of which were associated with the cell cycle and DNA replication. The most significantly downregulated gene in TBZ-treated cells was mini-chromosome maintenance protein 2 (MCM2). SiRNA knockdown of MCM2 inhibited proliferation, causing a G2/M arrest in GBM cell lines and suppressed invasion. Taken together, our results demonstrated that TBZ inhibited proliferation and invasion in GBM cells through targeting of MCM2.publishedVersio

Particle growth with photochemical age from new particle formation to haze in the winter of Beijing, China

Secondary aerosol formation in the aging process of primary emission is the main reason for haze pollution in eastern China. Pollution evolution with photochemical age was studied for the first time at a comprehensive field observation station during winter in Beijing. The photochemical age was used as an estimate of the time scale attributed to the aging process and was estimated from the ratio of toluene to benzene in this study. A low photochemical age indicates a fresh emission. The photochemical age of air masses during new particle formation (NPF) days was lower than that on haze days. In general, the strongest NPF events, along with a peak of the formation rate of 1.5 nm(J(1.5)) and 3 nmparticles (J(3)), were observed when the photochemical age was between 12 and 24 h while rarely took place with photochemical ages less than 12 h. When photochemical age was larger than 48 h, haze occurred and NPF was suppressed. The sources and sinks of nanoparticles had distinct relation with the photochemical age. Our results show that the condensation sink (CS) showed a valley with photochemical ages ranging from 12 to 24 h, while H2SO4 concentration showed no obvious trend with the photochemical age. The high concentrations of precursor vapours within an air mass lead to persistent nucleation with photochemical age ranging from 12 to 48 h in winter. Coincidently, the fast increase of PM2.5 mass was also observed during this range of photochemical age. Noteworthy, CS increased with the photochemical age on NPF days only, which is the likely reason for the observation that the PM2.5 mass increased faster with photochemical age on NPF days compared with other days. The evolution of particles with the photochemical age provides new insights into understanding how particles originating from NPF transform to haze pollution. (C) 2020 Elsevier B.V. All rights reserved.Peer reviewe